This story was last updated on Tuesday evening. For the latest information on Dorian, updated Wednesday, see: Tropical Storm Dorian intensifies as it nears Puerto Rico and is increasing threat to Southeast U.S.

A hurricane watch has been issued for Puerto Rico ahead of Tropical Storm Dorian, where conditions are forecast to begin deteriorating as early as Wednesday morning. The island is already under a tropical storm warning, with the threat of heavy rainfall and potential flash flooding and mudslides constituting the biggest concerns for the storm-weary island of 3.2 million.

“Our greatest concern is for the rain,” said Matthew Brewer, a meteorologist at the National Weather Service in San Juan. “We’re expecting between two and six inches, with local eight-inch amounts. We have some tight topography gradients, so flash flooding could be a problem.”

The island could see strong winds, too, although the winds will be only 10 to 20 percent of what the island experienced during Hurricane Maria, the Category 4 hurricane that devastated the island in 2017. Tropical-storm-force winds could begin as soon as Wednesday morning or afternoon.


Dorian over the Windward Islands as the sun rose Tuesday morning. (NOAA/TropicalTidbits.com)

As of Tuesday evening, Tropical Storm Dorian was centered about 275 miles southeast of Ponce, Puerto Rico, after moving directly over the island of St. Lucia. The system continued to fight dry air that is surrounding the storm, and its maximum sustained winds have remained around 50 mph since Monday night.

Radar data and hurricane hunter aircraft observations show that the storm has not yet closed off a consolidated center of circulation, which is holding back its intensification. Tropical Storm Dorian’s center of circulation reformed to the north of the previous center, the Hurricane Center stated Tuesday afternoon. This is an indication that the storm continues to try to intensify, but it’s struggling with ingesting dry air that inhibits thunderstorm activity near its core.

“It looks ragged on radar,” wrote Brian McNoldy, CWG’s tropical weather expert. “But the satellite presentation is the classic ‘CDO,’ or Central Dense Overcast, with fairly symmetric outflow and obvious banding. That is usually a predictor of intensification."

With their 11 p.m. briefing package on Tuesday, the National Hurricane Center predicted Dorian to strengthen overnight and for its peak winds to reach 65 mph before making landfall in Puerto Rico.

It’s important to note that, because of Dorian’s compact size, any subtle shift in track will have significant forecast implications. The National Weather Service in San Juan wrote that since “Tropical Storm Dorian is a small system, any change in the forecast track could affect the impacts.”

In Puerto Rico, communities are still recovering from Hurricane Maria, and the infrastructure on the island is still vulnerable, particularly the power grid. The biggest concerns with Dorian involve heavy rain, mudslides, and power outages.

According to the Associated Press, up to 30,000 homes still have blue tarps on them. On Monday, Governor Wanda Vázquez declared a state of emergency for Puerto Rico. Vázquez is new to the office after former governor Ricardo Rosselló resigned in late July under intense public pressure following a scandal involving leaked text messages between him and his political allies.


A "spaghetti plot" of ensemble members from the ECMWF model. These projections show Dorian is likely to continue its northwestward journey later this week. (Weatherbell.com)

Passage over Puerto Rico and its rugged terrain is expected to weaken Dorian some, but then it is forecast to re-strengthen as it passes over the warm water on the east side of the Turks and Caicos and the Bahamas Thursday and Friday.

By Saturday, the National Hurricane Center predicts Dorian to reach hurricane strength as it approaches the East Coast of Florida. A hurricane landfall along Florida’s east coast is possible Sunday or even further north into coastal Georgia or South Carolina.

“The threat of tropical storm or hurricane conditions, along with storm surge, in the Bahamas and along portions of the Florida east coast have increased,” the center wrote.

Two of the main global computer models forecasters use — the American GFS and the European ECMWF — have trended stronger with their intensity estimates since Monday. The National Hurricane Center has followed suit. On Monday, they were forecasting a 35-mph depression off the Florida coast Saturday night into Sunday morning. That forecast has increased to predicting a storm of hurricane strength.

For those with interests in the Florida peninsula, the best advice is to be aware of the latest forecasts and buy any needed supplies to complete your hurricane preparedness kit should the storm head that way.

Andrew Freedman and Jason Samenow contributed to this report.